Crystallization and preliminary X-ray studies of purine nucleoside phosphorylase from Cellulomonas sp

The commercially available enzyme purine nucleoside phosphorylase (PNP) from Cellulomonas sp. was purified by ion‐­exchange chromatography, partially sequenced and crystallized in two different crystal forms using the hanging‐drop vapour‐diffusion technique. Crystal form A grows as polyeders and/or cubes in the cubic space group P4232 with unit‐cell dimension a = 162.5 Å. Crystal form B appears as thick plates in the space group P212121 with unit‐cell dimensions a = 63.2, b = 108.3 and c = 117.4 Å. Both crystal forms contain three monomers (one trimer) in the asymmetric unit.